Door opening/closing mechanism

ABSTRACT

The present invention aims at providing a durable door opening/closing mechanism that does not require a large space for opening and closing operation and that a door and main body can be freely designed. To achieve this, a door is supported by links coupled to a cab by joints. One end of the door is guided along the side of the cab by a guide rail. When a rail support begins moving along the side of the cab while being guided by the guide rail, a couple of forces, causing the door to rotate, act on the joints at the both ends of the links. The other end of the door is swung out of the cab toward outside by the couple of forces, and the track is regulated into an arc form by the rod.

[0001] This patent application claims priority based on the Japanesepatent application, 2002-127038, filed on Apr. 26, 2002, the contents ofwhich are incorporated herein by reference.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] The present invention relates to a door opening/closing mechanismhaving a guide part to guide an opening and closing movement of the doorsupported by a support part.

[0004] 2. Related Art

[0005] Typical conventional door opening/closing mechanisms are of hingetype, sliding type, slide rail type, folding door type and swing armtype, which will be shown in the below explanation. Incidentally, thebelow explanation exemplifies on a door that is provided in a cab of aconstruction machine.

[0006]FIGS. 1A and 1B are plan views of conventional hinge-type dooropening/closing mechanism, while FIGS. 1C and 1D are front viewsthereof. FIGS. 1A and 1C show a door 2 a in a closed state and FIGS. 1Band 1D show the door 2 a in an opened state. This scheme has hinges 3 asa support part to support the door 2 a on a main body 1, as shown inFIGS. 1C and 1D. The door 2 a opens and closes describing an arcuatetrack 5 around an axis 4 of the hinge 3.

[0007]FIGS. 2A and 2B are plan views of a conventional sliding-type dooropening/closing mechanism, while FIGS. 2C and 2D are front viewsthereof. FIGS. 2A and 2C show a door 2 b in a closed state and FIGS. 2Band 2D show the door 2 b in an opened state. The sliding-type dooropening/closing mechanism employs a rail or the like in the guide partto guide the opening and closing movement of the door 2 b. Thus, thedoor 2 b is allowed to horizontally move, for opening/closing, on a sameplane of a side surface of the main body 1.

[0008] FIGS. 3A-3C are plan views of a conventional, general slide-railtype door opening/closing mechanism, while FIGS. 3D and 3E are frontviews thereof. FIGS. 3B and 3D show a door 2 c in a closed state andFIGS. 3C and 3E show the door 2 c in an opened state. The slide-railtype door opening/closing mechanism uses in its guide part a guide 7curved at one end, to be seen through a top window shown in FIG. 3A, toguide the upper part of the door 2 c, a rail 8 shown in FIGS. 3B-3E, anda roller 9 attached on the door 2 c. As shown in FIG. 3B-3E, the door 2c is allowed to open and close along the rail 8 while being kept nearlyparallel with an outer side surface of the main body 1. The door 2 c, inthe closed position, comes inward as shown in FIG. 3B because of thecurve provided at one end of the guide 7.

[0009]FIGS. 4A and 4B are plan views of a conventional, generalfolding-type door opening/closing mechanism, while FIGS. 4C and 4D arefront views thereof. FIGS. 4A and 4C show a door 2 d in a closed statewhile FIGS. 4B and 4D show the door 2 d in an opened state. Thefolding-type door opening/closing mechanism is structured with the door2 d divided in a plurality of vertical parts as shown in FIGS. 4A-4D.The divisional door parts in plurality are connected one another byhinges 3 or the like, to connect one ends thereof to the main body 1 byhinges 3. By folding the door parts as shown in FIGS. 4B and 4D, openingand closing operation is done.

[0010]FIGS. 5A and 5B are plan views of a conventional, generalswing-arm type door opening/closing mechanism, while FIGS. 5C and 5D arefront views thereof showing the arm 10 seen through therein. FIGS. 5Aand 5C show a door 2 e in a closed state and FIGS. 5B and 5D show thedoor 2 e in an opened state. The swing-arm type door opening/closingmechanism is structured with an arm 10 supporting the door 2 e on themain body 1 and a guide rod 11 having nearly the same length as that ofthe arm 10. As shown in FIGS. 5A and 5B, in this scheme, the arm 10 andthe guide rod 11 are allowed to simultaneously rotate around axes 10 a,11 a between the respective side and the main body 1. Due to this, thedoor 2 e opens and closes describing arcuate tracks 12 around the axes10 a, 11 a while being kept nearly in parallel with the side surface ofthe main body 1.

[0011] However, the conventional door opening/closing mechanisms involvethe following problems.

[0012] The hinge-type door opening/closing mechanism shown in FIGS.1A-1D is frequently used in buildings, vehicles and the like. However,it requires a large space such as the inside space of the arcuate track5 during opening and closing, shown in FIGS. 1A and 1B. This increasesthe amount of swing of the door 2 a out of the side surface of the mainbody 1, and makes the opening/closing operation difficult within alimited space. Also, because the door 2 a rotates vigorously if flappedby the wind in its opening/closing operation, a person who holds a gripattached on the door 2 a may be swung together with the door 2 a. In aconstruction machine, because the entrance/exit is located high and thestep is possibly narrow, there is an increased danger that the personmight fall. Meanwhile, when the door 2 a is opened, the end of the door2 a projects outward as shown in FIG. 1B. Consequently, when this doormechanism is used in the cab of a construction machine, a door of amachine room which locates at the rear of the cab is not allowed to openby the projected part. Also, because the axis 4 of the hinge 3 projectsfrom the side surface of the main body 1, a loss is caused in respect ofunit arrangement in the case that the machine overall width upontransporting is limited as in the construction machinery. Furthermore,there is a need to arrange the axes 4 of the upper and lower hinges 3 onone straight line. Due to this, a portion of the door to which thehinges 3 are attached must be in a straight-lined form, which imposesrestriction in designing a form of the door 2 a.

[0013] The sliding-type door opening/closing mechanism shown in FIGS.2A-2D is also frequently used in buildings, vehicles and the like. Thisscheme does not require a large space in opening and closing the door 2b. However, as shown in FIGS. 2A and 2B, the rail 6 which guides themovement of the door 2 b is always exposed outside so that the rail 6 isreadily rusted out and corroded due to rainwater, sea breezes or thelike, and adhered with sand dust or the like, making it impossible toobtain smooth operation. Consequently, an increased force may berequired for opening and closing the door 2 b, which possibly leads to atrouble. Also, it can be considered that the door 2 b be fallen off dueto worn-out guide surface in the rail 6. Also, the space where the door2 b moves parallel is needed in the inside of the main body 1. Thisreduces the efficient space in the inside of the main body 1corresponding to a door container. Besides, air-tightness is difficultto secure because of the opening/closing mechanism structure for thedoor 2 b to merely slide relative to the main body 1.

[0014] The slide-rail type door opening/closing mechanism shown in FIGS.3A-3E does not require a large space in opening and closing the door 2c. Also, because the door 2 c is closed at the inward due to guiding bythe guide 7, air-tightness is readily secured. However, because the rail8 is always exposed outside similarly to the sliding type door as shownin FIGS. 3B and 3C, the rail 8 is liable to rust and corrode due torainwater, sea breezes or the like, and adhered with sand dust or thelike, making it impossible to obtain smooth operation. Consequently, anincreased force may be required in opening and closing the door 2 c ordeformation or damage in parts may occur due to caught foreign matters,which possibly leads to a trouble. Also, because there are many specialformed parts, such as the guide 7, the rail 8 and the roller 9, used inthe guide part, the attaching part complicates in form and part costincreases. Also, the use of the rail 8 and the roller 9 in guiding thedoor 2 c increases the resistance due to sliding friction, requiringincreased force in opening and closing operation. Meanwhile, it can beconsidered that the door 2 c be fallen off due to wear in the guidesurface. Also, the rail 8 for guiding the door 2 c centrally positionsin the side surface of the main body 1, injuring the beauty of exteriordesign. Furthermore, as shown in FIG. 3A, particularly when the doormechanism of this type is applied to a vehicular cab or the like, thecurved guide 7 possibly blocks upper visibility of the top window.

[0015] In the folding type door opening/closing mechanism shown in FIGS.4A-4D, the angle between the door 2 d and the main body 1 side surfaceis nearly 90 degrees when the door 2 d is fully opened. Whether the door2 d is folded inward or outward of the cab, the protrusive amount of thedoor 2 d is great, requiring a large opening/closing space. Thus, for alimited space, there are many disadvantages in respect of unitarrangement or entrance/exit space. Meanwhile, for saving space when thedoor 2 d is folded, there is a need to make the door 2 d flat with arectangular outer shape, as a result the freedom in exterior design isrestricted. As can be seen from FIG. 4C, window frames occupy a largearea as the door 2 d is divided. This turns out smaller space forwindows. Where this type of door mechanism is applied to a vehicularcab, dead angle increases.

[0016] The swing-arm door opening/closing mechanism shown in FIGS. 5A-5Dmoves while being kept nearly in parallel with the side surface of themain body 1. During opening and closing, the door 2 e projects outwardfrom the side surface of the main body 1 by an amount corresponding tothe length of the arm 10 or guide rod 11. Consequently, in case a personstands in front of the door 2 e, the person is hit by the door 2 e.Also, it is not convenient in a narrow place such as nearby a wall wherethere is only a limited space outside the door 2 e. Also, the arm 10 islargely curved in order to prevent the arm 10 from contacting the mainbody 1 when the door 2 e is fully opened. Consequently, when the door 2e is closed, the effective space inside the door 2 e is limited by thecurved arm 10 as shown in FIG. 5A, causing great loss in respect ofinterior unit arrangement. Also, the arm 10 is attached generally at thecenter of the door 2 e while the guide rod 11 is attached at the frontor rear end of the door 2 e. However, because the other end of the door2 e is not restricted, the door 2 e chatters when the door 2 e is openedand closed.

SUMMARY OF THE INVENTION

[0017] The present invention is directed to solve such problems, andprovides a door opening/closing mechanism having a support partsupporting a door to a main body and a guide part for guiding a movementof the door during opening and closing, wherein the guide part makes oneend of the door for opening and closing move along an outer side surfaceof the main body, the support part supports the door to the main bodythrough joints, and regulates a track which is described, when the guidepart guides the one end of the door, by the other end of the door in anarcuate form.

[0018] According to this structure, when the opening/closing end of thedoor is moved along the outer side surface of the main body by the guidepart, a couple of forces which rotate the door act on the joints at theboth ends of the support part. The other end of the door describes anarcuate track while being swung out by the couple of forces.Accordingly, the opening/closing end of the door always moves along theouter side surface of the main body whereas the other end of the doorswings out of the outer side surface of the main body maximally to arcextension.

[0019] Consequently, because the door is swung out by the couple offorces occurred on the support part, the door can be opened and closedby a light operating force. Also, the opening/closing end of the doordoes not protrude from the side of the main body, a constantopening/closing space is always secured on the one end side of the door.Even where the outside of the door is narrow, opening/closing operationis facilitated. A person or object is easy to enter and exit. Meanwhile,because the protrusive amount of the other end of the door from the sideof the main body is suppressed to nearly the arc extension, the door canbe opened and closed even where the opening/closing space at the outsideof the door is narrow.

[0020] Meanwhile, because the door is always supported to the main bodyby the support part, there is no fear that the door falls out asencountered in the conventional slide or slide-rail door opening/closingmechanism. Also, because, unlike the conventional slide dooropening/closing mechanism in which the door is merely slide over themain body, the invention has the structure to put the lid on the openingof the main body by the door it is easy to secure air-tightness in themain body. Also, there is no restriction in exterior design, i.e. it isnot necessary to make the hinge attaching region of the door in astraight-lined form as in the conventional hinge-type dooropening/closing mechanism, or to expose the rail to the side of the mainbody as in the conventional slide-rail type door opening/closingmechanism. Also, there is no possibility of flapping by the wind duringopening and closing the door as encountered in the hinged dooropening/closing mechanism. Furthermore, the hinge axis does not projectto the side of the main body, not causing loss in respect of unitarrangement. Meanwhile, because the other end of the door is restrictedin movement by the support part, there is no chatter in the door when itis opened and closed.

[0021] Also, in the invention, the support part is structured bymultiple links supporting the door to the main body through the jointsand coupled one another by joints and a rod linked between the door andthe main body to regulate a track described by the other end of the doorin an arcuate form, and the guide part is structured by a guide railprovided inside of the main body along the outer side surface of themain body and a rail support moving along the guide rail in a coupledstate to the one end of the door through a joint.

[0022] According to this structure, the opening/closing end of the dooris guided together with the rail support coupled through the joint andmoved along the outer side surface of the main body by the guide rail. Acouple of forces to rotate the door act on the joints at the both endsof the multiple link. The other end of the door describes an arcuatetrack while being swung out by the couple of forces. On this occasion,the multiple pieces of links in a bent state support the door to themain body. The rod regulates a maximum of an arc extension of the trackdescribed by the other end of the door to its length. Also, the guiderail and rail support comprising the guide part are positioned inside ofthe main body.

[0023] Consequently, the amount that the other end of the door extendsfrom the side of the main body can be adjusted by selecting the lengthof the rod. It is possible to set the extension amount of the other endof the door depending on a set-up situation of the door. Furthermore,because the guide rail and the rail support are positioned within themain body, the external environment outside the main body does notaffect the internal of the main body. As a result, the guide rail is notinflicted in its smooth guide function due to rust-out or sand-dustadhesion as encountered in the conventional.

[0024] Also, in the invention, the support part is structured by asingle piece of link supporting the door to the main body through thejoints, and the guide part is structured by a guide rail provided insideof the main body along the outer side surface of the main body and arail support moving along the guide rail in a coupled state to the oneend of the door through a joint.

[0025] According to this structure, the opening/closing end of the dooris also guided together with the rail support and moved along the outerside surface of the main body by the guide rail. A couple of forces acton the joints at the both ends of the single link. The other end of thedoor describes an arcuate track while being swung out by the couple offorces. On this occasion, the single link supports the door to the mainbody and regulates a maximum of an arc extension of the track describedby the other end of the door to its length. Also, the guide rail andrail support comprising the guide part is positioned inside of the mainbody.

[0026] Consequently, the single link also has the function of the rod,so it is possible to omit the rode. As a result, the dooropening/closing mechanism becomes simple, and there is an increasedmerit in respect of manufacture cost or maintenance of the mechanism.Also, in this structure, because the guide rail and the rail supportcomprising the guide part are positioned within the main body, there isno possibility that the guide rail loses the smooth guide function.

[0027] Furthermore, in the invention, the support part supportsgenerally a center-of-gravity position of the door.

[0028] According to this structure, the load of the door is mainlyburdened by the support part, to reduce the burden on the guide part.Therefore, the door can be stably supported by the support part.

[0029] Consequently, there is a decrease in the operating resistanceacting on the guide part during opening and closing the door. The doorcan be opened and closed by a light operating force, owing to the coupleof forces caused on the joints at the both ends of the support part. Asa result, wear and deformation or the like rarely occurs at each regionof the support part and guide part, and the door can be smoothly openedand closed over a long term.

[0030] Also, in the invention, the guide rail has an end, fordetermining a closing position of the door, curved from a side of themain body toward inner side of the main body.

[0031] According to this structure, immediately before the closing ofthe door, the movement of the door in relation to the main body ischanged by a curved portion of the guide-rail from a state caused by astraight-lined portion of the guide-rail to be nearly in parallel withthe side surface of the main body into a rectangle angle to the sidesurface of the main body.

[0032] Consequently, in the case that an elastic member, such as rubber,for improving the air-tightness in the main body is provided between thedoor and the main body, when the door is closed, a pressure closing thedoor is exerted on the elastic member at an angle nearly rectangle tothe side of the main body. As a result, the attached elastic member isdeformed without unnatural strain and the life of the elastic member isprolonged. Also, because the elastic member becomes unlikely strippedoff and out of its shape, air-tightness is secured over a long term.

[0033] Also, in the invention, the joints are spherical joints for freerotation.

[0034] According to this structure, when conducting repair due toworsened attaching state of the door, deformation of the door or thelike, the dimensional error delicately occurring on the repaired doorcan be absorbed by free rotation of each of the joints around a centerof its sphere. Also, the repair and adjustment is not necessity for boththe door and the main body required in the conventional slide dooropening/closing mechanism, but only for the door.

[0035] Accordingly, it is easy to repair the door attaching, deformationor the like.

BRIEF DESCRIPTION OF THE DRAWINGS

[0036]FIGS. 1A and 1B are plan views of a conventional, generalhinge-type door opening/closing mechanism, and FIGS. 1C and 1D are frontviews thereof;

[0037]FIGS. 2A and 2B are plan views of a conventional, generalsliding-type door opening/closing mechanism, and FIGS. 2C and 2D arefront views thereof;

[0038]FIGS. 3A, 3B and 3C are plan views of a conventional, generalslide-rail type door opening/closing mechanism, and FIGS. 3D and 3E arefront views thereof;

[0039]FIGS. 4A and 4B are plan views of a conventional, generalfolding-type door opening/closing mechanism, and FIGS. 4C and 4D arefront views thereof;

[0040]FIGS. 5A and 5B are plan views of a conventional, generalswing-arm type door opening/closing mechanism, and FIGS. 5C and 5D arefront views thereof;

[0041]FIG. 6 is a side view of a crawler crane to which a dooropening/closing mechanism according to one embodiment of the presentinvention is applied;

[0042]FIG. 7A is a plan view of a cab of the crawler crane shown in FIG.6, FIG. 7B is a front view thereof, and FIGS. 7C and 7D are side viewsthereof;

[0043]FIG. 8A is a front view of a door opening/closing mechanismaccording to one embodiment of the invention as viewed from inside thecab, FIG. 8B is a plan view thereof when the door is closed, and FIG. 8Cis a plan view thereof when the door is opened;

[0044]FIGS. 9A and 9B are plan views of a door opening/closing mechanismaccording to one embodiment of the invention when a door is closed andopened, respectively, and FIGS. 9C and 9D are side views thereof whenthe door is closed and opened, respectively;

[0045]FIG. 10A is a plan view showing the state that a door iscompletely closed, in an opening/closing operation of the door accordingto the door opening/closing mechanism in one embodiment of theinvention, FIGS. 10B-10E are plan views thereof during opening andclosing the door, and FIG. 10G is a plan view showing full opening stateof the door;

[0046]FIG. 11A is a front view showing a state that an operatoropens/closes the cab door according to the door opening/closingmechanism of one embodiment of the invention, and FIG. 11B is a planview thereof;

[0047]FIG. 12 is a side view showing a door shape design exampleaccording to the door opening/closing mechanism of one embodiment of theinvention; and

[0048] FIGS. 13A-13G show modifications to the door opening/closingmechanism according to the invention, wherein FIG. 13A is a plan viewshowing a door opening/closing mechanism using a one-piece link, FIG.13B a plan view showing a door opening/closing mechanism using athree-piece link, FIG. 13C a plan view showing a door opening/closingmechanism using a straight-lined guide rail, FIG. 13D a plan viewshowing a door opening/closing mechanism using a one-piece link deviatedin support position, FIG. 13E a plan view showing a door opening/closingmechanism changed in operation procedure of a two-piece link, FIG. 13F aplan view showing a door opening/closing mechanism using a curved rod,and FIG. 13G a plan view showing a door opening/closing mechanism usinga toggle mechanism.

DESCRIPTION OF THE PREFERRED EMBODIMENT

[0049] Explanation will now be made on a case that a dooropening/closing mechanism according to one embodiment of the presentinvention comprising a support part having a two-joint link and a rodand a guide part having a curved guide rail is applied to a mobilecrane.

[0050]FIG. 6 is a side view of a crawler crane 13 to which a dooropening/closing mechanism according to the present embodiment isapplied. The crawler crane 13 is structured with a base carrier 13 a anda revolving super structure 13 b mounted thereon. The revolving superstructure 13 b has a cab 14 provided for an operator to get aboard. Ingetting on the cab 14, the operator first mounts a step 23 and thenopens a door 2 provided in the cab 14.

[0051] FIGS. 7A-7D show an exterior view of the cab 14 of the crawlercrane 13. FIG. 7A is a plan view of the cab 14, FIG. 7B is a front viewthereof, and FIGS. 7C and 7D are respectively a left side view and aright side view of the same. The door 2 appears in the left side view inFIG. 7C.

[0052]FIG. 8A is a front view of the door opening/closing mechanism ofthis embodiment as viewed from inside of the cab 14. FIG. 8B is a planview of the door opening/closing mechanism of the embodiment in a statethat the door 2 is closed. FIG. 8C is a plan view of the dooropening/closing mechanism of the embodiment in a state that the door 2is opened.

[0053] In the door opening/closing mechanism of the present embodiment,a guide rail 18 and an rail support 19 constitute a guide part formoving one end of the door 2 for opening and closing along an outer sidesurface of the cab 14. Links 16 a, 16 b and a rod 17 constitute asupport part for supporting the door 2 to the cab 14 and regulating atrack which is described, when the guide part guides the one end of thedoor 2, by the other end of the door 2 in an arc form. The door 2 issupported to the cab 14 by two pieces of links 16 a, 16 b. The links 16a, 16 b are defined a sequence of movement, as hereinafter referred, bynot-shown spring means acting to push the door 2 outside. The link 16 ahas one end coupled to nearly a center-of-gravity position of the door 2through a rotatable spherical joint 15, and the other end coupled to oneend of the link 16 b through a similar spherical joint 15. The other endof the link 16 b is coupled to the cab 14 by a similar spherical joint15 and positioned offset outward as shown in FIG. 8B.

[0054] In the lower part of the door 2, there are provided a guide rail18 for allowing the one end of the door 2, shown left in the figure, tomove along the outer side surface of the cab 14, and a rod 17 regulatinga track described by the other end of the door 2, shown right in thefigure, in an arc form. The rod 17 is linked between the door 2 and thecab 14, having a length set at approximately a half of an opening andclosing stroke of the door 2. Also, the guide rail 18 is attached to theone end of the door 2 in the inside of the cab 14 through the railsupport 19. The rail support 19, in a state coupled to the one end ofthe door 2 through a rotatable spherical joint 19 a, is allowed to movealong the guide rail 18. Incidentally, the guide rail 18 maybe laid inthe crane main body, e.g. beneath the floor plate of the cab 14.

[0055] The guide rail 18 has an end 18 a, defining a closure position ofthe door 2, curved from the side of the main-body of the cab 14 to aninner side of the cab 14. The form of the guide rail 18, although may bestraight-lined depending on a situation of the inside of the cab 14, canbe designed freely in consideration of tightness between the cab 14 andthe door 2. The door 2 has a lock 20 a to temporarily fix the door 2 ina close position. The rail support 19 has a door catcher 20 b shown inFIG. 8B. When the door catcher 20 b captures a striker 20 c shown inFIG. 8C, the door 2 is temporarily fixed in an open position.Incidentally, the door catcher 20 b is not limitedly attached on therail support 19 but may be directly mounted on the door 2.

[0056] As shown in FIG. 8A, two joints 15 are provided in a heightdirection at each connecting portion between the link 16 a and the door2 or between the link 16 b and the cab 14. In a closed position of thedoor 2 as shown in FIG. 8B, the support part and the guide part arearranged along inner surface of the cab 14 in a state that substantiallybeing same plane with the inner surface.

[0057]FIG. 9A is a plan view of the cab 14 when the door 2 is closed,while FIG. 9B is a plan view of the same when the door 2 is opened. FIG.9C is a perspective side view of the cab 14 as viewed from the outsidewhen the door 2 is closed, while FIG. 9D is a perspective side view ofthe cab 14 as viewed from the outside when the door 2 is opened. In bothFIGS. 9C and 9D, the links 16 a, 16 b are perspective. Note that, inFIGS. 9A-9D, the same elements as those in FIGS. 8A-8C are attached withthe same references and the explanation is omitted. As described above,during opening and closing the door 2, the one end of the door 2 isalways moved along the outer side surface of the cab 14 by the guiderail 18 and rail support 19, the other end of the door 2, shown by thechain line in FIGS. 9A, 9B, describes a track 21 of an arc.

[0058] In this structure, the door 2 is opened and closed in a manner asshown in FIGS. 10A-10F. FIGS. 10A-10F show the opening and closingoperation of the door 2, in 6 stages, according to the dooropening/closing mechanism of the embodiment. FIG. 10A shows the door 2completely closed, FIGS. 10B-10E show the states in the course of thedoor 2 being gradually opened, and FIG. 10F shows a state the door 2 isfully opened. Note that, in FIGS. 10A-10F, the same elements as those ofFIGS. 8A-8C are attached with the same references and explanationthereof is omitted.

[0059] In a state of FIG. 10A, as the lock 20 a of the door 2 isreleased and the opening/closing end of the door 2 begins to open, therail support 19 is guided by the guide rail 18 and caused to movetogether with the one end of the door 2 toward the right in the figurealong the outer side surface of the cab 14, as shown in FIG. 10B. Atthis time, a couple of forces act on the joints 15 at the both ends ofthe links 16 a and 16 b, to cause rotational motion of the door 2. Theother end of the door 2 is swung out of the cab 14 by the couple offorces. At the same time, the rod 17 is swung out, together with theother end of the door 2, around the axis in the outer side surface ofthe cab 14. As for the links 16 a, 16 b, only the link 16 a is firstswung out as shown in the figure.

[0060] The other end of the door 2, as shown in FIG. 10C, increasinglyswings out of the outer side surface of the cab 14 while describing anarcuate track. Simultaneously, the one end of the door 2 moves rightwardin the figure along the outer side surface of the cab 14. At this time,the link 16 a is maximized in its swing amount. As the one end of thedoor 2 is further operated rightward in the figure, the rod 17 increasesthe angle relative to the outer side surface of the cab 14 as shown inFIG. 10D, reaching a maximized swing amount out of the outer sidesurface of the cab 14. From then on, the link 16 b is swung out aroundthe joint 15 in the outer side surface of the cab 14.

[0061] When the door 2 reaches a position shown in FIG. 10E, the link 16a is brought into abutment against the inner surface of the door 2 andstopped rotating. Then, with movement of the door 2, only the link 16 bcontinues rotating rightward in the figure while being restricted by therod 17. When the one end of the door 2 is further operated toward theright to reach a position shown in FIG. 10F, the link 16 b and the rod17 stop rotating whereby the door 2 is fully opened nearly parallel withthe side surface of the cab 14. On this occasion, because the doorcatcher 20 b captures the striker 20 c, the door 2 is fixed in an openedstate. Meanwhile, at this time, because one end of the link 16 b on theside of the cab 14 is offset outward, the cab 14 and the links 16 a, 16b can be prevented from contacting with each other.

[0062] The operation of closing the door 2 is done in the order reverseto that of opening the door 2. In this case, the movement of the door 2relative to the cab 14 is as follows. Namely, the movement of the door2, at immediately before closure, is changed by the curved portion ofthe guide rail 18 from a state nearly parallel with the guide rail 18 toan angle toward a rectangle to the main-body side surface of the cab 14.

[0063] According to the door opening/closing mechanism of theembodiment, when the opening/closing end of the door 2 is moved alongthe side surface of the cab 14 by the guide rail 18 as described above,a couple of forces act on the joints 15 at both ends of the links 16 a,16 b to cause rotational movement of the door 2. At this time, the otherend of the door 2 describes an arcuate track while being swung out bythe couple of forces. Consequently, the opening/closing end of the door2 is allowed to always move along the outer side surface of the cab 14whereas the other end of the door 2 swings, maximally to an arcextension, out of the side surface of the cab 14. Thus, because the door2 is swung out by the couple of forces acting upon the links 16 a, 16 b,the door 2 can be opened and closed by a light operation force.Meanwhile, because of no protrusion at the opening/closing end of thedoor 2 from the side surface of the cab 14, a constant opening/closingspace is always secured on the side of the one end of the door 2,allowing the operator to get on/out with safety. Also, because the swingof the other end of the door 2 out of the side surface of the cab 14 canbe suppressed nearly to an extent of arc extension, the door 2 can beopened and closed even where the opening/closing space is narrow on anouter side of the door 2.

[0064]FIGS. 11A and 11B show the states that the operator 22 opens andcloses the door 2 of the cab 14. FIG. 11A is a front view showing astate that the operator 22 is on the step 23 to open/close the door 2when the operator 22 gets on/out the cab 12. FIG. 11B is a plan viewshowing a position of the operator 22 and a track of opening/closing thedoor 2 when the operator 22 is opening/closing the door 2 of the cab 14.Note that, in FIGS. 11A and 11B, the same elements as those of FIGS.10A-10F are attached with the same references to omit the explanationthereof. As shown in the figure, the operator 22 can avoid contactingwith the opening/closing door 2 by standing on the narrow step 23 of thecrawler crane 13 in a opening/closing space secured on the one side ofthe door 2. Accordingly, the operator 22 does not suffer from unstablepostures and does not fall off or down.

[0065] Meanwhile, because the door 2 is always supported to the cab 14by the links 16 a, 16 b, there is no fear that the door 2 falls out asencountered in the conventional slide or slide-rail door opening/closingmechanism. Also, unlike the conventional slide door opening/closingmechanism in which merely the door 2 slides over the cab 14, the presentembodiment has the structure to put the lid on the opening of the cab 14by the door 2 so that it is easy to secure air-tightness in the cab 14.Also, there is no danger that the door is flapped by the wind whenopening and closing as encountered in the conventional hinge-type dooropening/closing mechanism. Furthermore, the axis 4 of a hinge 3 does notproject to the side of the main body, and loss does not cause in respectof space or freedom of the unit arrangement within the cab 14. Also, theuse of two pieces of links 16 a, 16 b makes it possible to arrange thesupport part of the door 2 within a space of the cab 14 equivalent tothe thickness of the door 2. This improves a machine operationperformance and a operator's resident performance in the cab 14.Meanwhile, because the other end of the door 2 is regulated in movementby the links 16 a, 16 b and rod 17, there is no chatter of the door 2when opening and closing the door 2.

[0066] Also, there is no possibility of restriction in exterior design,such that a shape of the portion of the door 2 a to which the hinges 3are attached is made in a straight-lined shape as encountered in theconventional hinged door opening/closing mechanism or such that the rail8 is exposed on the side of the main body as in the conventionalslide-rail door opening/closing mechanism. Accordingly, it is possibleto design the upper side 2A of the door 2 not parallel with the lowerside 2B as shown in the left side view of FIG. 12, or to design the leftend of the door 2 in a form two lines 2C, 2D are polygonal instead of astraight line form. Furthermore, it can be designed in a continuouscurved line.

[0067] In this embodiment, when the other end of the door 2 describes anarcuate track while being swung out by a couple of forces, the links 16a, 16 b in a bent state support the door 2 to the cab 14 while the rod17 regulates, to its length, the maximum of the extension of an arcdescribed by the other end of the door 2. Consequently, the swing of theother end of the door 2 out of the side surface of the cab 14 can beadjusted by selecting a length of the rod 17. It is possible to set aswing amount of the other end of the door 2 depending on a set-upsituation of the door 2. Furthermore, because the guide rail 18 and therail support 19 are positioned within the cab 14, the externalenvironment of the cab 14 does not affect the internal of the cab 14. Asa result, the guide rail 18 is not inflicted in its smooth guidefunction due to rust-out or sand-dust adhesion as encountered in theconventional.

[0068] According to the door opening/closing mechanism of thisembodiment, because the links 16 a, 16 b support the door 2 at aroundits center-of-gravity position, the load of the door 2 is mainlyburdened by the links 16 a and 16 b to reduce the burden on the guiderail 18 or rail support 19. Thus, the door 2 is stably held by the links16 a and 16 b. This reduces the operating resistance acting on the guiderail 18 and rail support 19 during opening and closing the door 2. Thedoor 2 is to be opened and closed by a couple of forces caused upon thejoints 15 at both ends of the links 16 a, 16 b due to light operationforce. As a result, less wear or deformation takes places in each partof the links 16 a, 16 b, guide rail 18 and rail support 19, allowing tosmoothly open and close the door 2 over a long term.

[0069] According to the door opening/closing mechanism of thisembodiment, as noted before, the movement of the door 2 relative to thecab 14 is as follows. Namely, the movement of the door 2 in a statenearly parallel with the side surface of the cab 14 by thestraight-lined portion of the guide rail 18, at immediately beforeclosing, is changed to an angle toward a rectangle direction to the sidesurface of the cab 14. Consequently, in the case in which a packing ofan elastic member, such as a rubber, is provided between the door 2 andthe cab 14 to improve the tightness in the cab 14, when the door 2 isclosed, the packing is pressed by a pressure closing the door 2 innearly a rectangle direction to the side surface of the cab 14.Accordingly, the attached packing deforms with natural strain,increasing the life thereof. Also, because the packing is not readilystripped off and out of shape, stable air tightness can be kept over along term.

[0070] Also, according to the door opening/closing mechanism of theembodiment, the joints 15, 19 a are spherical joints for free rotation.Accordingly, when repair is conducted due to worsened attaching state ofthe door 2 or deformation of the door 2 or the like, the dimensionalerror delicately occurring on the repaired door 2 can be absorbed byfree rotation of each of the joints 15, 19 a around a center of itssphere. Also, there is no necessity for the repair and adjustment forincluding both the door 2 and the main body required in the conventionalslide door opening/closing mechanism. Repair and adjustment issatisfactory only for the door 2. Due to this, the door 2 is easy toattach, repair deformation or the like or maintain.

[0071] Although the above explanation is for the door opening/closingmechanism using multiple pieces of links as exemplified by the twopieces, the door opening/closing mechanism of the invention can use asingle piece of link 24 to omit the rod 17, as shown in FIG. 13A. Notethat, in FIG. 13A, the same elements as those of FIGS. 10A-10F areattached with same references and explanation thereof is omitted. Theopening/closing mechanism of the door 2 is realized by eliminating therod 17 in FIGS. 8A-8C, and using a single piece of link 24 instead ofthe two pieces of links 16 a, 16 b.

[0072] Also in this structure, when the door 2 begins to open, the railsupport 19 coupled to one end of the door 2 is guided by the guide rail18 to move along the outer surface of the cab 14, similarly to thestructure having two pieces of links. At this time, a couple of forces,causing rotational motion to the door 2, act on the joints 15 at theboth ends of the link 24. The other end of the door 2 describes anarcuate track while being swung out of the cab 14 by the couple offorces. On this occasion, the link 24 supports the door 2 to the cab 14and regulates, to its length, a maximum value of extension of an arcdescribed by the other end of the door 2.

[0073] According to the door opening/closing mechanism with the onepiece of link 24, the link 24 has also a function of the rod 17, so itis possible to omit the rod 17. As a result, the door opening/closingmechanism is simplified in structure, increasing the merit in respect ofmanufacture cost and maintenance of the door opening/closing mechanism.

[0074] Incidentally, the above explained on the case in which the guidepart uses the guide rail 18 and the rail support 19 while support partuses the two pieces of or one piece of link, several modifications areto be considered in the invention as shown in FIGS. 13B-13G. Note that,in FIGS. 13B-13G, the same elements as those of FIGS. 10A-10F areattached with the same references and explanation thereof is omitted.

[0075] As shown in FIG. 13B, in case three pieces of links 25 a, 25 b,25 c are used in the support part of the door 2, the effect is obtainedsimilar to that using two pieces of links 16 a, 16 b. Also, astraight-lined guide rail 18 a can be used as shown in FIG. 13C,allowing for free form of design. Meanwhile, although in the aboveexplanation the support part holds nearly the center-of-gravity positionof the door 2, there is no limitation in support position for the door2. As shown in FIG. 13D, a single piece of link 24 can be used tosupport the end of the door 2. Also, as shown in FIG. 13D, the link 24can be arranged outer than the outer shape of the door 2. Also, it ispossible to invert the operation order of the two pieces of links 16 a,16 b explained in the embodiment, e.g. the link 16 b can be first swungout, as shown in FIG. 13E. Also, the links 16 a, 16 b may not be givenorder in operation so that both can rotate simultaneously when the lock20 a shown in FIG. 8A is released. As shown in FIG. 13F, the rod 17,besides the link 16 b, is made curved at its end to decrease theswing-out amount of the door 2 when the door 2 is fully opened. Also,although the joints in the links 16 a, 16 b can be freely arranged, asshown in FIG. 13G, a toggle mechanism may be provided in the joints 26of the links 16 a, 16 b to omit the lock 20 a, 20 b, 20 c.

[0076] Meanwhile, although in the above explanation the guide rod 17 wasstructured by one rod-formed member, it can be made by a plurality ofpieces of links such as the links 16 a, 16 b. Also, the guide rod 17 orlink 24 may be structured to expand and contract, as an expansion rod ofthe automotive antenna or crane's telescope type jib. By providing atrigger mechanism or the like for determining the operation sequence ofmultiple pieces of links to cause, when one link rotates a predeterminedangle, another link to start swing out, it is possible to omit the guiderail 18 and rail support 19 or the rod 17 or all of them. Also, the lockmechanism which determines opening closing position of the door 2 may bearbitrary in attaching position. The lock may position the rod 17 at theother end of the door 2 or restrict rotating of the link 16 a, 16 b, 24.Also, latches or locks can be added in the constituent parts in order tofix the door 2 in an intermediate position.

[0077] Meanwhile, although in the above explanation, the joint 15between the door 2 and the link 16 a is positioned in a state alignedwith an axis direction of the link 16 b in a closed position of the door2 as shown in FIG. 8B. However, the joint 15 between the door 2 and thelink 16 a maybe positioned outer toward outside of the cab 14 than theaxis direction of the link 16 b in a closed position of the door 2. Thispositioning makes the swinging out action of the door 2 smooth, when thedoor 2 is opened.

[0078] Meanwhile, the above was explained on the case in which theinvention is applied to the cab 14 of the mobile crane 13, the inventionis not limited to this but can be similarly applied to the entrance,window, lid or the like of various structures.

[0079] Although the present invention has been explained in reference tothe embodiments, it is apparent for those skilled in the art that manychanges and modifications can be made without departing from the spiritand scope of the invention, as clear from the following claims.

What is claimed is:
 1. A door opening/closing mechanism having a supportpart supporting a door to a main body and a guide part for guiding amovement of the door during opening and closing, wherein: the guide partmakes one end of the door for opening and closing move along an outerside surface of the main body, and the support part supports the door tothe main body through joints and regulates a track which is described,when the guide part guides the one end of the door, by the other end ofthe door in an arcuate form.
 2. A door opening/closing mechanismaccording to claim 1, wherein the support part comprises multiple piecesof links supporting the door to the main body through the joints andcoupled one another by joints and a rod linked between the door and themain body to regulate a track described by the other end of the door inan arcuate form, and the guide part comprises a guide rail providedinside of the main body along the outer side surface of the main bodyand a rail support moving along the guide rail while being coupled tothe one end of the door through a joint.
 3. A door opening/closingmechanism according to claim 1, wherein the support part comprises asingle piece of link supporting the door to the main body through thejoints, and the guide part comprises a guide rail provided inside of themain body along the outer side surface of the main body and a railsupport moving along the guide rail while being coupled to the one endof the door through a joint.
 4. A door opening/closing mechanismaccording to claim 2 or 3, wherein the link supports substantially acenter-of-gravity position of the door.
 5. A door opening/closingmechanism according to claim 2 or 3, wherein the guide rail has an end,for determining a closing position of the door, curved from a side ofthe main body toward inner side of the main body.
 6. A dooropening/closing mechanism according to any one of claims 1 to 3, whereinthe joints are spherical joints of free rotation.
 7. A dooropening/closing mechanism according to claim 2, wherein the guide railhas an end, for determining a closing position of the door, curved froma side of the main body toward inner side of the main body, and thejoints are spherical joints of free rotation.
 8. A door opening/closingmechanism according to claim 2, wherein the multiple pieces of links arestructured by a first link connected to the door through the joint and asecond link connected to the main body through the joint, and the jointbetween the door and the first link is positioned outer toward outsideof the main body than an axis direction of the second link in a closedposition of the door.
 9. A door opening/closing mechanism according toclaim 2 or 3, wherein two joints are provided in a height direction ateach connecting portion between the link and the door or between thelink and the main body.
 10. A door opening/closing mechanism accordingto any one of claims 1 to 3, wherein in a closed position of the door,the support part and the guide part are arranged along inner surface ofthe main body in a state that substantially being same plane with theinner surface.